The invention relates to a semiconductor target having a radiation-sensitive layer for converting radiation into electrical signals, the radiation-sensitive layer, on the side of the incident radiation, having at least one electrode which is permeable to that radiation.
The invention also relates to a target assembly for a camera tube which has such a semiconductor target and is provided with a window on one side of the target which passes the radiation incident on the radiation-sensitive layer. The target is further provided with a support such as a ring of electrically insulating material.
The invention furthermore, relates to a camera tube comprising such a target assembly, and to a method of manufacturing the target assembly.
Targets and target assemblies of the type described above are generally known. The charge image and potential image, respectively, generated by the radiation (which may be both of an electromagnetic and of a corpuscular nature, in accordance with the application) are scanned by an electron beam and the electrical signals originating from the electrode(s) are further processed as a picture signal in a circuit arrangement suitable for that purpose.
The signals originating from the electrode or electrodes will in general, first be supplied to a sub-circuit which provides at its output the signal in a transformed form, for example in an amplified form, a signal with an impedance transformation or delay, which is then supplied for further processing to the remaining part of the circuit.
For high signal-to-noise ratio, it is of great importance that the signal originating from the electrode(s) should be supplied to the subcircuit via a capacitance which is as low as possible. This often presents problems in known target assemblies in which the electrodes of the target are connected, inter alia, to the camera tube holder and hence provide a rather large input capacitance.